Why did the water started to flow outside ?

 There is a empty glass jar with a hole at the top . Now glass jar is filled half with

 water . Meanwhile a balloon is fully blown and was tied to the mouth of jar

 completely covering it.

Now something weird happens . As soon as we cover the mouth of jar with fully

 blown balloon , the water which was at the bottom of jar now rises up and starts

 to flow through the hole which is at the top . Water continue to flow out till all the

 air inside the balloon gets zero .

Now what is the reason behind this ? This is definitely not a witchcraft . It is the

 science experiment on atmospheric pressure of air .

Now when we started to fill the jar with water  , we were doing it in atmospheric

 pressure of air . Now when the fully blown balloon is tied to the mouth of jar then

 volume of the air increases .

With temperature remaining same and according to Charles law , volume is

 directly proportional to pressure . Hence pressure of air becomes more than

 atmospheric pressure .

Now air starts putting this extra pressure on already there water . Meaning it tries

 to displace the water from inside of jar . Water finds a way to go out through the

 hole .

This process continue till all the extra pressure from air comes back to

 atmospheric pressure of air which was earlier .

Surely I had goosebumps when I saw water started to flow outside all of a sudden !!