I filled a cart with a coffee 18mg PG mix. There was previously a little bit of my 24mg VG pineapple mix left over, but I had a bit to drink and I didn't really care and didn't think mixing the two would cause any harm. I filled my cart, vaped for a bit, and hooked my ecig up to charge while I slept, leaving the cart hooked up to the atty overnight which I usually do anyway. I only clean it every other day, so I usually don't bother even taking it out. That morning, I hooked my battery back up to the atty, took a hit, and got a dry, crackling sound, followed by very little vapor and a bad taste. I took the cart off, and the e liquid had dried up to more of a gooey substance and had caked on the inside of the cart. My atty looked okay, but I had to give it a hardcore cleaning twice before the coffee taste went away. It still made some popping sounds for an hour or two afterwards, but now everything is back to normal and it hits like new again. I threw the cart away, because it was pretty bad. Fill was ruined and I didn't feel up to scraping it clean. Any idea what happened here? It confused me and I really don't want it to happen again 
I know...boo...hiss
