Usually I have trouble acquiring items, but in 1.11 with a mending fishing rod I'm starting to have a problem I've never had before... too much junk.
So I built a simple incinerator, consisting of a single lava block hidden in my stone floor, with a dropper immediately above it to hide it. This was inset in the wall, and had a button to activate. A little tedious collecting all 80 saddles and 2000 boots (I exaggerate only slightly), put them in, and soon things are back to normal.
That is, until the spontaneous fires occurred. I don't use very many flammable blocks, so it was more shocking than harming, but I wasn't aware that air blocks above lava can catch fire spontaneously even if covered.
How deep do I have to put the lava so that the stone floor doesn't burst into flames? I've got at least 5 or 6 depth that I can use for this.