Nicole Scherzinger suffered an enormous burn down her entire leg after boiling hot water was dropped on her ... but that didn't stop this Pussycat Doll from performing one hell of a show.

Taking to her Instagram Stories on Sunday ... the singer shared a gruesome photo of her blistering injury she suffered amid the Pussycat Dolls' European tour.

Over the gnarly pic ... Nicole wrote ... "Nothing like boiling water falling on your leg an hour before your set. But the show must go on."

It seems that not only did the show go on ... but so did Nicole.

Nicole and the rest of the Pussycat Dolls graced the stage at the PSD Bank Dome in Düsseldorf Saturday ... before the band's Amsterdam show tonight.

In Sunday's post, Nicole added ... "Thanks Düsseldorf for keeping me going. See you soon Amsterdam."

We hope you heal quickly, Nicole!