We were camping last week and got tree sap (I think it was pine) on the windshield of our car? We tried soap and water with little success. Turning on the windshield wipers also did not work (smudged it around).
Does anyone know how to remove it?
If you're looking for a lifehack v. a dedicated product, I would go down this road:
Temperature will be key. If the sap is still in a rather large clump, ice works great. The sap will contract at a different rate than the glass, and usually dislodge in a rather large piece.
If it has smeared (I suspect it has), you will need to get it warm. Maybe a piece of black paper underneath the affected area and leave it in the sun, possible steam, or other sources of heat that won't damage your glass (no blowtorches). Paper towels will help quite a bit if you can get it hot enough. For any remaining residue, dissolving it in copious amounts of alcohol(ethanol is best) is the only sure-fire way I'm aware of.
Most solvents will remove sap and since this is a windshield you don't have to worry about paint! (Just be careful when applying). Try some of these that most people have around: hand sanitizer, rubbing alcohol, alcohol wipes, wd40, acetone or if you want to kill 2 birds use RainX (contains alcohol).
They also sell specific products for this car part stores (Tar and goo remover).
Be sure to remove any large chunks with a razor first and then clean up the residue.
Most paint supply stores will sell you a pint of MEK or Methyl Ethyl Ketone. That will remove or dissolve almost anything including sap, surgical plastic, most petroleum distillates, and acrylics.