Rust

Aquascope does a little visualization of what's going on behind the scenes. cs.brown.edu made it for their rust book experiment: https://cognitive-engineering-lab.github.io/aquascope/

Learn Rust With Entirely Too Many Linked Lists is a great example of how references work (or don't work) in more complex situations. Might seem like a lot at first, but working through writing the code yourself and seeing the compiler's responses is a great help when learning Rust. It also doesn't hurt to read it once and then come back and read it again later, after you try writing some more programs.