My minecraft sever will load for a few seconds and then crash my whole game and kick me out.

Put the summary of the bug you're having here
My game is crashing when I get on a world.
What I expected to happen was...:
I thought it wouldn't kick me off when I tried at different times, but it still kicked me off
Describe what you thought should happen here
I thought it would let on and let me play Minecraft
What actually happened was...:
I was repeatedly kicked off of the Minecraft server and brought back to the Minecraft laucher
Describe what happened here

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. I log in
3. Then I click on a world
4.Then it lets me go in
5.After a few seconds it crashes my whole game
6.It will take me to Minecraft launcher page