We tried to break a 25g cesium (caesium) ampoule in the air, but it started to rain. The bomb group helped us with a detonating cord.
This is one experiment from "100+ experiments in chemistry" collection at http://www.chemicum.com/chemistry-videos experiments .

tseesium ja vesi
cesio en el agua
césio em água
Cäsium in Wasser
цезия в воде
césium dans de l'eau
tseesiumi reaktsioon veega