@ khyam
dry ice is chilled/frozen carbondioxide, sublimation takes place in icecream hawker's cabin. sublimation in layman terms is when mater changes its state from solid to gas without being ever converted to liquid state. the dry ice trays in their cabins change to vapors so there is no liquid to mess up inside the cabin.
and yes you can make a small bomb/explosion from dry ice., dont ask me how to make one.:-#
terrorists might be visiting PW. and then express news would say,
" lahore k aik busy area main thanda bomb phat gaya" lol.