be bursting to do something
be bursting to (do something)
To feel a strong desire or impulse to do something. We were all bursting to tell you about the surprise party—it's a miracle it was still a surprise!
See also: burst
be bursting to do something(informal) want to do something so much that you can hardly stop yourself: She was just bursting to tell us the news.
I’m bursting when it is used on its own usually means ‘I really need to go to the toilet’.