This is a favorite of kids and teenagers: dry ice bombs. Put some dry ice in a plastic bottle filled with water, screw the lid tight, and run away. The dry ice sublimates producing carbon dioxide gas. One kilogram of dry ice can produce about 16 cubic feet of gas, which is quite a large volume expansion. The gas produced inside the bottles leads to a pressure buildup that produces its explosive rupture.
Filming these explosions underwater with high-speed cameras has produced some amazing footage that illustrates scientific principles regarding pressure waves and how they travel through water and air.
However, making these bombs is very hazardous. Not only can they explode unpredictably, but the very loud sound from the explosions can cause hearing loss, and pieces of shrapnel from the bottle or small pieces of leftover dry ice can damage the skin or eyes. Over the years many injuries have been reported in the United States as a result of both accidental and intended detonations of dry ice bombs, and it is illegal to make these devices in several states.