Actually on a Galaxy Tab S2 (I had to tell it, so...), I noticed a bug some days ago.
When a Shulker (the mob, not the box) is placed down, and recieves a lava flow on it, the mob starts to glitch. It randomly teleports as usual, but then returns into the lava, where it was. It glitches a little, teleports again, and it continues forever, even if the lava is removed.

There is apparently no way to stop it (maybe hitting it, but it is teleporting too fast), since the lava doesn't hurt it. I hope this will be useful, I didn't see any bug like this in the first pages.