Subject: What makes heat focus at the tip of a soldering gun?

I have a soldering gun here, and the heat is transferred to an 8-inch long 
piece of copper wire, which is bent in the middle (it looks like a V but the 
bend is not so pronounced as a V). Most of the copper wire is hot, but not 
nearly as hot as the tip. I've tried putting the bend in another part of the 
wire, and that part then becomes the hottest. What principle of physics is at 
work here?

Re: What makes heat focus at the tip of a soldering gun?