I know that either of these scenes were not my first experiences of seeing something with this theme, but they definitely stick out in my mind.
Village of The Giants is a classic. And I remember how erotic it was seeing Joy Harmon pop open her cardigan as she grew. You don't see anything, but it's a sexy little scene. I love EUF, so I always wish she were wearing a bra underneath. But you can't deny the embarrassment and implied nudity is great.
The other one is more of a lady forcefully stripped than a pure ENF/EUF scene. And that is I Come in Peace. I Come in Peace is a Dolph Lundgren b-movie sci fi flick from the 80s about an intergalactic drug dealer. Yep, pure 80s sci-fi cheese. The main baddie injects drugs into people's chests and then collects the adrenaline to sell. This method means ripping open people's shirts. So of course, he eventually finds a female to collect from. He gets a hold of a female mechanic, and I clearly remember watching her top get ripped open to show her bra-covered chest and thinking that was super hot. Unfortunately, she gets a spike in her head a few minutes later (not as graphic as it sounds, thankfully), but a hot a little scene until that point! I've attached an admittedly not great screen capture, but you can find the flick on YouTube to see it in better quality.