Yes, Chris, I've felt that very often. I just experienced it on Tabata Something Else after restarting my Crossfit routines from a long layoff. It may have something to do with it, as my muscles aren't used to storing as much glycogen as before, but it's also just the body running out of fuel. My heart was pounding afterwards and I felt cold and weak, like I was going to puke or pass out. I just insist on training in the mornings before I've eaten because out of the 3-4 hours of free time in my day, it is best for my schedule. I may have to buy some food bars just to get something going through my system, but it'll be an experiment.
Prior to Crossfit, I was also starved because I hadn't eaten for over 12 hours at morning PT and sprints killed me. I went into racing heart and cold sweats and couldn't recover. My sergeant at the time made me go and get water and I passed out on the way there.
I'm pretty sure it has to do with the body running out of fuel and it's worse when you're deconditioned because you can't sense when you're low. I haven't had an episode doing evening workouts with a preworkout snack. See if that works for you and try easing into Crossfit a little more. I've personally learned the price of cutting corners. Best of luck!