bubble = emotion bubble. Usually a happy feeling or a high. Then you get some terrible news and the bubble bursts. If you burst my bubble, then you ruin all my fun.

It means the surprise was spoilt for you. Example: A.: So are you happy with the car your parents are going to buy you for your birthday? B: No , I didn't know. "Talk about bursting my bubble."

"bursting my bubble" Ruining my hopes. or Ruining my excitement.