Teflon tubing in nozzle throat coming out?
It looks like you got too tight nozzle, too cold hotend or extruding speed is too high (all could be in the same time of course).
As filament goes into the teflon tube (coldend) and then into hotend it doesn't have enough time to go out throught the nozzle. So it causes that melted filament accumulates in hotend and pushes out teflon tube.

Check application and arduino settings for 


nozzle diameter (increase it), check if it's not plugged with something inside
hotend temperature (increase it), check for your filament settings
extrude ratio (decrease it), check also gearing on extruder motor