Smokescreen on Demand by Bryce Hixson
Ammonium nitrate and zinc dust are gently poured into a metal bottle cap and mixed thoroughtly. Two drops of water are added to the mixture and several seconds later the contents start to smoke and then burst into flames. Great demo for change of state and exothermic reactions. Handy to know if you are ever responsible for your own special effects as an extra on a James Bond movie.