Guess first.  Discover next. 

1. Does an onion float in water?
2. What happens when a whole, unpeeled onion is frozen then thawed?

I discovered something interesting during the frozen onion experiment.
 It takes a bit of imagination, but you, too, may make the discovery.
 Possibly, later, in a separate category I will mention my discovery;
 meanwhile, you are welcome to mention yours!