Can People Be Allergic to Water?

OK, it's not technically an allergy, but yes: People can have extreme skin reactions to water. Learn more in this episode of BrainStuff.

Here is the setup. Take a clear plastic (or glass) drinking glass. Fill it with cool tap water. Let it sit on the counter for a couple of hours. In some cases you will come back to find dozens of small bubbles clinging to the inside of the glass. why?