Ceramic tiles break for many reasons. Manufacturers test tiles, especially those manufactured for use on flooring, to ensure they meet certain specific standards before shipping them. Most floor tiles must be able to withstand 113 Kilogram of force according to the standards. Assuming that something heavy did not fall on the tile from above, it is frequently the subfloor underneath the tiles that causes the problems that lead to broken ceramic tiles.
When an installer lays tile directly over concrete, movement or shifting of the concrete may cause cracking in the tile. Concrete shrinks as it sets and may appear to have set on the surface before it has cured all the way through. Tiles applied over a concrete surface that is still shrinking will get pulled together and split apart. This is called reflective cracking.
Tenting is similar in cause to reflective cracking, only instead of tiles splitting they will buckle at the grout seams. As concrete shrinks it creates shear pressure. If the shear pressure is greater than the bond strength of the adhesive used to hold the tiles down, tiles may lift and suffer damage.
Deflection can occur in ceramic tile that is installed over wood. Deflection occurs when a wooden subfloor warps. Warping of the surface to which tiles are attached will inherently force the tiles themselves to move. In most cases, deflection will only split the grout. In extreme cases, however, it is also possible that deflection may damage the tiles themselves. This differs frorm reflective cracking you see with concrete in that as concrete shrinks, it pulls the tiles together. With deflection, the wooden surface buckles upward and pushes the tile out and snaps either the grout or actual tiles.