What would occur if you attached a bicycle tyre to a pump, and pumped on it indefinitely...?
Suppose you took an ordinary balloon, and started blowing into it. Could you do this indefinitely?
As you well know, you could do no such a thing. At some point the balloon would break. The pressure inside the balloon would be too great for the balloon to contain, and rupture would occur. The same effect would occur if you were to inflate a bicycle tyre to bursting point with a bicycle pump.
A gas will expand to fill all available volume. As the pressure on the outside of the balloon is reduced, the gas inside the membrane (inside the balloon) will expand to fill the newly available volume. At some point the balloon will rupture.
A more practical (and more dangerous) illustration of this principle occurs for scuba divers. Scuba divers are trained NEVER to hold their breaths. Upon ascent, the gas expands inside their lungs, and if there is no means of exit, their lungs will rupture; divers are trained to perform emergency ascents with continual EXHALATION so that the air pressure in their lungs may be reduced.
I cannot find it, but on youtube somewhere there is a video of a guy whose aerobic capacity is so well-developed, that he can take a hot-water bottle (you know what these things are, right?) and blow it up to bursting as you would a balloon.
I was pretty impressed. Of course, before he does the business, he SHOULD don a pair of safety spectacles so that his mince pies are protected from the rubber of the bottle. What a prat!