The only thing that could make me pop by looking at it would be my own brain or insides so that i would have to pop to see it. If that's not a start to finding the answer then maybe the riddle is just one of those 'booby prize' ones with a really stink answer. That's the problem when you have a hard riddle but no-one has the guarantee that there is an answer worth the effort of finding it.
Also nothing makes me cry but onions. But i doubt they are a significant part of the polar bear diet and it's unlikely to be what makes their fur white. What else really makes people cry and pop?
