Adam Rubin answers this question in his book Big Bad Bubble.
The bubbles end up in La La Land. Which isn't all bad because it is where donuts grow on trees! However La La Land is also where monsters live and they are afraid of bubbles. They run away screaming whenever they see a bubble. Summer is the worst time for the monsters since there are more bubbles in the summer months.
What will the monsters do? Will they learn the truth about bubbles? Are monsters afraid of anything else? This is a fun read aloud that I am sure your entire family will enjoy.
After reading the story go out and make some bubbles!
Happy Daily Reading