I think Diyisfun was probably quite lucky. Sometimes tiles come away from sand/cement easy as pie (even when you don't want them to). Other times they practically get completely assimilated into the slab. This depends on a whole raft of factors, such as tile structure, sand/cement mixture used, even the humidity and temperature on the day they were laid.
I prefer to get the tiles to lift before removing the grout. If you put the slightest nick in the edge of the tile, it will create a week point that will cause the tile to snap under further manipulation.
My favorite tool for lifting the tiles when I want to reuse them is a steel ruler. (the thinner the better). Anything like a bolster or chissel, once inserted more than a couple of millimetres forces the edge of the tile up, and therefore snaps it (as it is still held down in the middle).
Tap the steel ruler under the edge of the tile and when it won't go in any further, tap it from side to side to clear the channel, then in further, etc.. Eventually either, the whole tile pops off
, or a bit of it does
Just don't try to lever the tile up at any time, or it will probably snap.
I am being serious this time, but it's still only a suggestion.
