Why does my hot water sometimes sound like popcorn?

That popcorn noise drove me nuts when I first moved in. I did a bunch of reading and ended up flushing the tank a couple times, but it never really went away. Our water’s not super hard, but there’s definitely some mineral content—enough that I see white buildup on faucets. I’ve wondered if a water softener would make a bigger difference than just using a sediment filter? Or maybe I’m overthinking it and just need to get on a regular flush schedule. Anyone ever actually see the inside of their tank after years of this? I’m half tempted to open mine up just to see how bad it is...