If two soap bubbles of different radii are connected by a tube :

We know that the excess of pressure inside the soap bubble is inversely proportional to radius of soap bubble, i.e., p∝1/r where r is the radius of the bubble' Therefore, the pressure inside the smaller bubble is greater than inside a bigger bubble. As a result, when both bubbles are connected by a tube, the air flows from smaller bubble to bigger bubble. So, the bigger bubble grows at the expense of smaller one'