When bubbles float away, where do they go?

On Earth, Bobby wonders where the bubbles go after they float away. 667 million light years away, Bibble, an alien, wonders where bubbles come from. So Bibble makes himself a spaceship of bubbles and flies to earth, where he meets Bobby. Unable to speak each other’s language, they use bubbles to become friends. Of course, it is soon time for Bibble to go home, but Bobby won’t forget him.