If the pressure inside the tank grows to a level exceeding that at which the safety relief valve can expel it from the tank, the propane tank may rupture. If flames or a source of ignition is present, the propane will ignite resulting in an explosion.
What you should do is to wet a side of the cylinder with water, after a while the used top part will be dry while the lower part with gas will remain wet.
The wet portion will indicate the amount of propane (gas) left in the tank.
Most times we shake our gas cylinders to know if it’s finished or not, that’s a dangerous thing to do. It could be suicidal according to post on Facebook.
You can save a life today by sharing this information.