This one is very simple, but I've seen it quite a few times lately. It hurts my head.
I'd like to think it's because the person's finger twitched, or because autocorrect is out to get us. I'm pretty confident that's what it is.
Just in case it isn't...
"Too" means the same thing as "additionally" or "extremely."
I'm seeing my doctor. I ate way too much toothpaste.
I'm headed for the doctor too! Let's carpool.
"To" means things like "toward" or "until."
When he got home, he felt hungry and went straight to the toothpaste drawer.
It's quarter to four AM and all I can think about is toothpaste.
There are many, many other definitions of the word "to," so I won't get into those. The most important thing to remember is the use of "too."
Switch out the "too" for "extremely" or "additionally." Does it look right?
I was going too the doctor's office, but I got caught up in eating more toothpaste.
I was going [extremely/additionally] the doctor's office, but I got caught up in eating more toothpaste.
Pretty obvious, right? Perfect. That's exactly how it should be. Remember the switch trick and you'll be good forever.