This is a classic experiment and it is very easy to do at home. So after you watch it - TRY IT! All you need is some kind of volcano that you can make, and then a little vinegar and some baking soda from the supermarket. This demonstration shows an acid base reaction. In this kind of reaction, the acid (vinegar) chemically reacts with the base (the baking soda) and the two release carbon dioxide gas which bubbles out. The liquid soap helps to make foamy lava that flows.
Full step by step directions can be found at:http://www.sciencebob.com/experiments/volcano.php