I had the same freak out yesterday while changing my power steering pump on my 08 4.6L 4x4. I couldn't see anything that the tube was meant to run to and haven't had any problems while driving.

 

Looks to be a vent tube (front 4x4 axle). Tube needs to be high enough so that water or mud cannot get into it when 4 wheeling, hense the reason for its "open" location.

 

I looked it over again today while I was cleaning my Throttle Body and MAF and yes it is in fact a very small diameter tube and I again traced it back to the back side of the drivers side hub. I cut about an inch and a half of the end where I had melted it.

 

It's the iwe actuator vent tube. There's one on the passenger side also.

 

Yes lewissa81 I just googled that term and sure enough that is what it is, mystery solved. I guess I'm fine having just cut 1 1/2inch of it then.