Chumba Wumba, which is the boss you fight at the top of the volcano at the end of the captain gunn quest line, used to drop a chest approximately 6 or 7 years ago. He currently does not drop a boss chest, which makes it impossible to get his unique weapon, the tub thumper, without spending crowns on the second chance chest. I had to spend around 1000 crowns to get it, which is absurd to have to do because of a bug. Videos from around 2013 and before show Chumba Wumba dropping his boss chest, but videos from around 2014 and onward do not show this and my experience farming the boss supports this. I farmed this on my privateer a few dozen times and did not get a boss chest once. I even farmed on my witchdoctor and my musketeer for a while and still dod not get a boss chest to drop from him once. The boss appears in the instance quest "Into The Fire". Attached is a screenshot of only the minion chests appearing after I beat him one of the times.
https://imgur.com/i05pvJb

Sticky note added ;).