explode a bombshell

[explode a bombshell] {v. phr.}, {informal} To say somethingstartling; suggest or show something astonishing or shocking,

Thepolice exploded a bombshell when they arrested the kindly old bankerfor stealing money from the bank.

The principal exploded abombshell by cancelling the dance as a penalty.

Political leadersexploded a bombshell when they picked the young lawyer to run formayor.