Chew gum or suck on a breath mint. When you swallow it will help equalize the pressure changes in your ears and get rid of the "bubbles".
Because of the dramatic air pressure change.
It caused by change in pressure. When internal air pressure is higher than of surrounding it causes your ears to pop.
atmospheric
As one increases in altitude pressure decreases. The pressure in your ears is then higher than the pressure of the air so one feels tension in their ears.
There is low air pressure usually when you are up in a mountain or in an airplane like when your ears pop after you get in an airplane and you are at high altitude your ears do this because the pressure inside your ears and the pressure in the air is not the same. When there low air pressure the air is less dense.
As the plane climbs, the pressure drops, even in a pressure cabin. The pop is your ears equalizing from ground pressure to altitude pressure.
Because of the pressure build up in your ears.
When you climb higher the air pressure changes and the pressure inside of you hasn't changed so the pressure makes your ears hurt. After a while the pressure balances out and your ears wont hurt. That is why cabins are pressurized to help reduced pain from pressure difference.
Ears "pop" when there is a change in pressure. It is the bodys way to prevent discomfort from pressure changes.
Because the water is forcing bubbles from you and it is sucking all the air out of your ears which causes the pressure to hurt.
The popping is a result of your body/head adjusting to the pressure differences while on the plane.
This also frequently occurs on landing mainly because of the difference in air pressure.