The refit Enterprise was shown being destroyed on television ads for Star Trek III, before the film was released. Maybe movie trailers too, though I don't recall right now. It was hard not to understand what was happening, since a sizable chunk of the saucer was blown away.
Yeah, now that you mention it, one of my best friends from grade school told me that, but fortunately he didn't tell me until well after I saw the movie.
As I've mentioned before, I had no idea...going in spoiler free...so I got the full effect of the Enterprise blowing up.
30 years later and I can *still* remember EXACTLY what I thought and felt when I saw the scene.