I'm not entirely sure if @StanRogers answer covers it entirely so I'll add this.
When you use compressed air canisters several things happen besides the blast of air which can (as Stan describes) remove things like the thin film coating.
First, the gas, stored under pressure expands quickly, this gas expands because its heating up and has room (less pressure) to move, therefore changing phase. Gas that expands rapidly takes heat away from its surroundings very quickly in order to do that. So what your essentially doing is drawing heat away very quickly which is what leads to the liquid state you describe in your question.
If you invert the can (or shake it) and spray onto a piece of black leather or something, you'll notice a pool of something that looks like water that evaporates very quickly and leaves a white residue.
The liquid is the gas (and propellant depending on brand) which boils and turns to air. The white residue is condensed moisture (aka ice!).
Now, the important thing about most materials is that they don't like thermal shock, things that are a few atoms thick and crystalline (like sapphire!) especially dislike thermal shock. So, if you suddenly drop and the temperature can reach −50 °C!! This could potentially damage the coating and the glass and at the very least weaken the structure. So if you follow it up with a hard blast of air, that could be what it needs to catastrophically fail.
Hopefully that helps!