The phrase 'to burst someone's bubble' means to destroy their fantasy or illusion of something.
I had a great idea for a new website, until George burst my bubble and told me someone had already got there first.
I'm sorry to burst your bubble, but the party has been cancelled.
I hate to burst your bubble, but you won't be getting a pay rise this year.
Don't confuse it with
When something 'bubbles up' it means it rises or appears suddenly. For example:
Anger and unrest have been bubbling up across parts of the city today.
Melody Yang is the daughter of Fan Yang, the founder of Canadian theatre group, 'The Gazillion Bubble Show'. As a family, they have broken numerous world records for their bubble displays, most recently for encapsulating 181 people in a 50 metre long soap bubble. Fan advises that to make good bubbles, you need to mix dishwasher liquid, baking soda and glycerine with clear water.