If you're using LME & boil all of it,that's your problem. It caramelizes pretty easy. DME not so much. I do partial boils with 1.5-2lbs plain DME,adding remaing DME & all the LME at flame out.
Since pasteurization happens at 162F,the wort is still hot enough at 180F+ to do the job. Anyway,it'll be lighter colored & cleaner flavored. Especially if you control ferment temps & chill the wort down in 20 minutes or less.