Something intresting

I've asked this question before and never got a satisfactory answer. The only two possibilities is that the facehugger jumped with enough force to break the glass, or it used a form of quick dissolving acid.

The problem with the first possibility is that the facehugger would need clairvoyance in order to know that bone crushing force was required instead of a simple grab if it was to break through his helmet. The problem with the second possibility is similar to the first, mainly how the facehugger would know that the helmet was artificial and not part of its host's face. Also, how would the facehugger cause the acid to stop after it had burned through the helmet?

I did have 1 thought, seeing as the facehuggers are in liquid maybe said liquid is alkali in composer. Thus neutralising any acid used to try and burn through the containment tube. The liquid may also answer your first point. Because, if the liquid is viscous in composer building enough momentum to break it would be extremely difficult (without the use of arms, or other similar upper body appendages).
Just a thought.

In the first movie the facehugger jumped out from the egg, as we've seen in the AVP movies facehuggers can catch some serious air. The hugger in Aliens had no room in that tube, couldn't power it's legs. I think the liquid also played a big role in containment as you've stated.

The only way to get the true answer to this, is to contact the holy Berg, he would be the one to know.

The facehugger has two big... balls... right? Maybe one is filled with the embryo in a kind of hybernation that will keep it from developing too soon and the other has a limited supply of acid. Either that, or the facehugger has a limited supply of expandable acid in some sacks around its "mouth". Personally, i think the theory that those two balls are breathing sacks is folly, because even between preds and humans, they don't breathe the same gas, and for a creature on a distant planet that can survive without breathing to have two sacks of Earth air hanging from its body would be a pretty dumb coincidence. And about the clarvoyance, obviously no, the facehugger would only need that big portion of immobile spine-like bone structure that its body is composed of to be filled with brain and that would already be a bigger brain than dogs have, which is pretty big for such a small creature. Dogs are pretty smart creatures who can even not bump like idiots into a piece of glass so i'm thinking a facehugger could also tell the difference between glass and your head.