It's Saturday. It's hot. Let's pop some water balloons in slow motion, shall we?
Water Balloon vs. Face
From Discovery's Time Warp, around 0:36 the balloon finally pops after molding itself to the man's face. From there it's all wet.
Popping a Water Balloon
When that volume of water is suddenly unsupported by its balloon container, it stays remarkably cohesive...until it doesn't.
Let's drop some water balloons and see if they bounce.
A Giant Water Balloon Popping
Skip to 4:12 if you just want to see the burst minus the prelude. It takes them a bunch of tries to make this thing pop.
Smarter Every Day's Water Balloon Adventures
After an intro to "bullet art," we see a variety of slo-mo balloon pops (starting about 1:00 in).
A surprisingly beautiful ad for Schweppes beverages, featuring lots of water balloons in slow motion, along with nice music ("To Build a Home"). Basically this video combines all the effects seen above.