Yes, you can remove much of it with oooo super fine steel wool and some polishing compound.
Ironically, I just had to do this earlier today. My wife came back from Nevada where she parked our truck next to a sprinkler. NOTHING would remove the spots from the glass. I had to use Meguirs Fine Cut cleaner to buff them out.
I got something called "Glass Scrub" a couple years ago at Advance Auto. It's in a squeeze bottle like car wax and it removes pretty much anything, sap, paint overspray, adhesives...it even takes the "yellowing" off old plastic headlight lenses.
Have had the same tube since, so don't know if it's still available.
Cut a potato in half and rub it against the glass. Works wonders on glassware in the kitchen also that have mineral stains from the dishwasher. use a bit of vinegar for the large spots or a bit of a lubricant if you find the potato sticking to the glass alot.