This is a fun chemical reaction that often goes under the name of elephant toothpaste, obviously because it looks like giant toothpaste.
This is a pretty cool reaction because it only requires hydrogen peroxide (H2O2,) yeast dissolved in water and dish soap. And bam “toothpaste”
The great thing is the only byproducts are water, soap and oxygen. Clean up is easy, no harmful toxins. Great for showing kids and adults alike the wonders of chemistry! (beware, this is an exothermic reaction and puts off a lot of heat — if you try it at home take safety precautions to avoid burns.)