Science is absolutely awesome.
There's nowhere you can go and nothing you can do that cannot be analyzed scientifically.
Take a look at these amazing and mesmerizing Vines of science experiments, and learn how to do them yourself!
Runaway black pepper:
What's going on: The ground black pepper rests on top of the water due to surface tension. Pepper is hydrophobic, which means it doesn't like water, and won't dissolve in it, so they just sit there with nowhere else to go. When a dish soap-covered finger is placed in the middle of the peppered puddle, the surface tension is drastically reduced. The water that hasn't lost its surface tension tries to run away from the soap, which then carries the pepper to the edges as it goes.
What's going on: This reaction works for the same reason as the runaway black pepper. As the surface tension on the milk is disturbed by a soap-soaked cotton swab, the milk tries to run away and ends up swirling the colors together in the process. The longer it is held in place, the more it will swirl. If you want to make this more fun, try introducing soap at multiple points in the milk in order to change up the swirling pattern.
What's going on: When potassium iodide is introduced to hydrogen peroxide, the exothermic reaction happens very quickly. Oxygen is released rapidly, and it gets caught as bubbles from the liquid dish soap that is added into the mix. This experiment is often called "elephant toothpaste," and a yeast/warm water mixture can replace the potassium iodide to decompose the hydrogen peroxide.
What's going on: The slime-like substance shown above is called oobleck. It is a non-Newtonian fluid, which means it doesn't behave the way Isaac Newton said that liquids should. While oobleck — which is only two parts cornstarch to one part water— can flow though fingers or form a soft puddle just like a normal liquid, it acts as a solid when force is applied. If you have enough oobleck, you can even walk on it.
What's going on: Based on the non-Newtonian properties described above, sound waves that are long and loud enough can provide enough force to make the oobleck dance. Simply secure plastic wrap over the speaker and crank up the volume. To make it more fun, add a couple drops of food coloring and let the oobleck mix the colors together.
What's going on: This exothermic (heat-releasing) reaction that looks like you have released the kraken is what happens when Mercury(II) thiocyanate (Hg(SCN)2) is set on fire and produces a solid mass. Toxic fumes are created with this experiment, so it probably isn't a good idea to do this outside of a chemistry lab that has the right ventilation. A similar (but slightly less nightmare-inducing) version of this can be safely done using 'black snake' fireworks.
What's going on: In order to burn, fire needs access to oxygen. Putting an inverted glass over the candle into water seals off the candle's oxygen supply, and uses up all of the oxygen. The gases that remain have lower pressures, which causes a vacuum to form inside the glass, pulling the water up.
(Side note: the coloring in the water just makes the experiment easier to see, and isn't necessary for the reaction)
Flammable smoke trail:
What's going on: Look closely. After the candle is blown out, a lighter creates a new flame, even though they're several inches apart. This happens because the smoke still contains molecules that are flammable. When a new flame is introduced higher up along that trail of smoke, it actually catches on fire and traces back down to the candle, re-lighting it.
Cover image: Screen shot of Kristen Elliott's experiment