I did that once. I had asked for a raise and didn't get one. I let my boss know I'd be looking elsewhere. Still didn't get one. Found another job and accepted i

I did that once. I had asked for a raise and didn't get one. I let my boss know I'd be looking elsewhere. Still didn't get one. Found another job and accepted it and quit the old job which promptly resulted in an offer of a large raise on the old job - larger than the salary at the new place. The old job was right next door to me and the new one across town. I went to the new place with a huge gift basket and apologized and explained that I wouldn't be starting after all because I got a counter offer I couldn't turn down. They looked stunned. I left. I worked at the old place another several years and ended up rising to Director of Operations before leaving to work on my own company. I still feel bad about it but it was the right decision overall.