This band almost blew off the stage, what a gig it was. （Is this a correct sentence）
This band almost blew off the stage, what a gig it was. （Is this a correct sentence）

Question

This band almost blew off the stage, what a gig it was.  （Is this a correct sentence）
This band almost blew off the stage, what a gig it was.  （Is this a correct sentence）

Answer

It's a little odd, unless it was an outdoor concert and it was very windy. If you want to say that it was an excellent, exciting concert, then you could  say "the band almost blew the roof off".

Answer

Or, "The band almost blew the stage away". Not an idiom, like "blow the roof off", but it would make sense if you trying to be creative.