Aha...now that is interesting. I always salt the water in my pans when boiling veg etc; and also when boiling eggs because if an egg cracks the salty water seems to seal the crack and the egg doesn't flow out.
Does that mean the water will take longer to boil with salt in it?
200 and odd degrees or so, I think (might be able to check with my jam-making thermometer, around September, possibly!) but there's another thread inviting scientific answers to a vaguely similar question here.