If you butt the all the tiles without any spacing, will the tile crack or bubble up due the expand and contract?
as was mentioned the grout lines help to allow for small or large diferences in size. The grout also makes the seal between the tile to keep water from leaking between.
You should always leave a little gap for a grout joint. Variations in tile size does occur and the gap allows for this. Nearly all stone material expands and contracts with heat and cold so the possibility of your tiles cracking, becoming drummy or lifting are increased by not having a gap.
you could, but moreover you need the space even as little as 1/16 th to keep the tiles from each other so they don't break/chip while rubbing together at setting. all tiles are not exactly the same in size and the grout helps its appearance in keeping straight lines in the setting of tiles. (satillo's are more irregular and need 1/2 to allow for sizing)...as for the bubbles, not sure what you're referring to. go to home depot or Lowe's for correct mud to set your tiles in and grout to separate and fill the gap. there used to be brass that could be used between the tiles, but that's plenty pesos.
I have butted 12 x 12 marble tiles together without a grout line, but it was a small entry area. I lived there for several years without any problems. Marble, however, is very slick when people come into your home with feet shoes or feet.
