The King of Random shows us how to make sparklers, shaken butter (that you can turn into a candle), instant ice (tutorial), and melting metal with microwave parts. [more inside]
Got some dry ice? Got a swimming pool? Well, what are you waiting for? Inquisitive dogs will be confused! Start with a small chunk. Next, take a 60-pound block of dry ice and kick it into the jacuzzi. Okay, so you're looking for more of a thrill? Try a dry ice depth charge! (If you don't have a pool, a frozen lake will do.)
Walking on liquids, corn starch rocking out to the beat of a subwoofer and materials that expand as they stretch are just some of the cool videos mentioned in The Stuff of Dreams (plenty more links in the last link).