This morning I made my kid a batida--a fruit shake. I put about 1/4 pound of fresh papaya, half a banana, a lick of sugar and a glass of milk in the blender until it was smooth. Her dad and I helped her out with it, but we didn't manage to polish it off, so I left her still-half-full sports cup in the sink when we went out for the day. Attending to the breakfast dishes some ten hours later, I found that what was a thick shake this morning had solidified to the consistency of a gelatin-enhanced mousse. Turning the cup over, nothing poured out. I poked my finger into it and it left a hole.
Can anyone explain this?