The tile popping up is a temperature versus improper installation situation.
Tile and concrete are of different density, hence they expand and contract at different rates. That is the reason for tile grout. Tile grout expands and contracts. For years (and sadly--to this day) tile setters did not use grout. I was expensive and deemed useless. They grouted the tile with cement or used the thinset as grout. This does not allow for expansion and contraction. When the temperature gets cold for a few days the concrete structures actually shrink. And up pop the tiles as they contract at a different rate. Every popped tile I have seen here was grouted with cement or cement based thinset.