I had a screw-top bottle of sauvignon blanc. I forget the maker, cost about $15, more than I usually spend on everyday wine. I don't usually drink white, but had it for my daughter who prefers it. Anyway, she had a glassful and put the bottle back in the fridge. No more than two days later, I thought I'd pour a glass for myself so I didn't have to open another bottle. As it filled the glass, it looked a little light, like almost water light. Took a sip. It bore little resemblance to wine, or alcohol, mostly like water with a hint of something else. It wasn't vinegar-y or off. It was close to water, both in taste and color. My DD said it tasted fine when she had a glass. I usually find that refrigerated white wine will keep quite a few days.
This happened once before, different white wine, turning back to water.
Has this ever happened to you? What's going on?