Is this normal?

Tweet

My kitty has been vomiting a lot recently. It's not the type of vomit when he's eaten something he shouldn't - I've seen my share of that. A good part of the time, he doesn't actually throw up anything. And it seems to be well placed. He's always doing this in my range of sight. At least within my range of hearing. I never walk into a room to see he's gotten sick. I always know about it when he's doing it. Sometimes he does this on books or things of mine. He never does it around his litterbox or food bowl. He's otherwise extremely friendly. Like always. Is kitty-kitty trying to tell me something? Is he mad at me for something? Could he be stressed about something? Does that cause this? I guess what I want to know is do cats cause themselves to vomit or could this only be related to something he can't control? Please help!!!