lance the boil

To take a decisive and dramatic action that resolves or puts an end to a problematic, troublesome, or unpleasant situation. It's high time that we as citizens use the power of our vote to lance the boil of corruption in Washington! If we can't speak openly about employees being mistreated, we'll never be able to lance the boil for good.

lance the boil

take decisive action to put an end to an undesirable situation.

The underlying image is of a boil being cut open with a lancet or other sharp surgical instrument, to release its pus.

2003 Yorkshire Post Today Mr Conway … said…it was time for Mr Duncan Smith to ‘lance the boil’ in his leadership. ‘There's a growing feeling of “it's got to end”.’