How to avoid air bubble under the floor ceramic-tile?
By "no other covering over it" - I assume you mean you didn't properly prep the sub floor, and so you put down ceramic tile over an uneven surface.

Which means you didn't "develop" an air bubble (an air bubble won't form under inflexible ceramic tile like it will under vinyl), but rather, you put the tile down over voids, so there was nothing to support the tile.

The ONLY fix for this is to remove the tile completely, level the floor (I suggest floor leveling compound), then put down a layer of Ditra (orange grid flexible underlayment that protects the tile itself), then the appropriate depth of mastic and re-tile.

There is no other way to fix an improperly prepared subsurface when dealing with rigid tiles like ceramic.