Https://tls.ulfheim.net/ has a beautiful graphical way to see every step of setting up a TLS connection. This is porn for network geeks, but also for hackers (sometimes the same people).
To paraphrase Ultra Famous Hacking God Pablos Holman, Here’s the messages between website and client to set up TLS. Every one of these is an interaction, and we can throw broken stuff at every one of them. Send a zero when it’s expecting one, send longer data than expected, and just see what breaks and falls in your lap.
That’s where things get really interesting. 😉