So here's what ya do. Buy some dry
ice (wherever possible.) Then either find or get an empty PLASTIC bottle with the
cap still there and intact. Then pour
water into the bottle (the more you put in the less time you have to run), put cubes of ice in (the more you put in the less time you have and the larger the explosion), twist on
cap TIGHTLY and throw immediately. Can work in any time frame from 30 sec. to 2 min., and is incredibly loud. The reason you must do it in a plastic bottle is so that glass shrapnel doesn't go anywhere and kill people.
Here's how it works:
Dry ice is so cold that it goes from a solid to a
gas, skipping the liquid phase. Since
gas is less dense, it will expand ALOT and will eventually explode. I have never tried it without
water, but it probably would either take to long or not work