Twice I have seen magicians use clear balls which were then punctured and dissolved as water. They didn't handle like jelly or balloons, but as solid objects which, when punctured, released their water and collapsed. Anyone know what these are, and where I can find them?

Only can suggest you contact the people you seen do this. I only seen such things on Star Trek movies and televisions shows. Something like this is out of the range of selling a trick at a magic shop or website.

Do you remember who was the magicians you're talking about ?

Hi there!
You might be referring to a product called spitballs by a company called dunecraft..
It's available on Amazon.. I think I remember seeing this on wizard wars.. The balls become invisible when under the water, but look like orbs of water and can 'explode'' and become invisible in the water again.
Gotta love science!

You are actually looking for Water Balz Jumbo 2. Here is a link https://www.youtube.com/watch?v=IPK2m0qRZx4

I believe this is one of the magicians in question. It is all very clever manipulation. https://www.youtube.com/watch?v=lnmnVcTDacU