Minecraft keeps running after shutting down through task manager

I'm not sure if this is a launcher or game-based bug, but it doesn't seem like intended behaviour.

How to reproduce:
1. Load up a game and alt+tab to the desktop
2. Start windows task manager and close minecraft from the tab "applications"
3. Minecraft disappears from the tab and taskbar, but game sounds can still be heard and "Java Platform SE binary" can still be seen in the "processes" tab in task manager. Can be repeated to cause a cacophony of game sounds.