Soap films and foams are great for popular science experiments. This is an attempt to collect a few ideas.

Giant soap bubbles
Giant soap films
Demonstration of surface tension by putting a soft loop into a large film, then distroying the loop in the film -> becomes circular

Frame to measure surface tension by hand
Plateau frames , which are out of plane
Put a person in a cylindrical bubble
Interference effects with soap films
Large-scale antifoaming (impressive...)

Beer: two beer bottles – hit one on top of each other – the one which is hit foams an awful lot!