Guys can you suggest some good models for my expo related to chemistry please please.... as the following are some models i have already choose let your suggestion somewhat be cool like this.

1. putting pepper on water and touching it with soap water (all goes away your hand in the beaker)
2. instant water freeze
3. growing ice
thats all please help



My  suggestion  is
3..growing ice

can u please suggest some more ideas and not the left one