I found a fun experiment on Pin Interest. http://preschoolpowolpackets.blogspot.com/2012/01/science-experiment-elephant-toothpaste.html . I decided to try it out with Matthew, but of course I didn't have everything that I needed so I had to make due. I only had only 3% hydrogen peroxide. I know that it said that the this experiment wouldn't work with 3%, but I wanted to try anyway.
As it turns out, this experiment is still kinda interesting. It does not explode quickly, but it slowly rises up and starts to bubble up. You should try it out with your kiddos!
Here's some pictures of what happened for us. Matthew still enjoyed playing with the bubbles after we were done.
Sorry for the darkness on some of these....