The cabin and hold of a plane are both pressurized to the same level but when the aircraft is flying at crusing altitude of about 37,000ft, the cabin pressure is significantly lower than the pressure when you took off. Cabin pressure should never fall below the pressure equivalent to an external altitude of 8,000ft. Even at this altitude, the air pressure in the cabin is only 75% of the pressure at ground level. At ground level, the air pressure is typically about 15 pounds per square inch. At 8,000 feet this falls to less than 12 pounds per square inch meaning that a container that is two square inches in surface area experiences what would be like a six pound (3 kilogramme) weight sitting on it at ground level. This can be enough to rupture some packaging.
You can minimize problems with squashable tubes by squeezing the air out and putting the lid back on again. The problem tends to be that as the air pressure drops, the air inside the tube expands and can force contents out of the cap (especially if it's flip top) or even burst the bottom.
Anyone who wants to have a little fun with air pressure can take one of the empty mineral water bottles they usually give with meals on long haul flights and put the lid back on tightly at cruising altitude. Hang onto it until you land (you might need to hide it to stop the flight attendants collecting it as rubbish) and it will have imploded on itself.
