It's a chemical reaction to keep the molecules from reacting with air over time. It's magic:headscratch:. All I know is it does work. I've been storing motorcycles during the cold season for almost 40 years. I learned the hard way that gasoline turns to a varnish like substance as some of the chemicals evaporate. Carb jets and needles plug up and require a rebuild. Stabil keeps it from happening. I just started my bike for the first time in 4 months and it fired up with ONE KICK. I use Stabil in the stang, all 4 of my bikes, lawnmower, snow blower, weed wacker and any thing else that has gasoline. Actually, now when I buy gas for the mower and other small engines, I just mix Stabil right in the gas can. By the way, pump gas can go bad within 30 days.I've never put anything in the gas. Do you know how the stuff works or is it just magic?
The water you saw was condensation in the exhaust. Your short drive warmed it enough to form the condensation, but not enough to dry it out. This is common to all cars in colder, damper climates.