What part of the sentence is the subordinate clause
Eric worked until the boss told him to go home.

"until the boss told him to go home"

Explanation:

Eric worked until the boss told him to go home.

Also referred to as a dependent clause, a subordinate clause is one which complements a sentence's main clause.  I've underlined the main clause and italicized the subordinate clause.  You can see that "Eric worked" could stand alone as a sentence, but "until the boss told him to go home" could not.  

he chooses to climb mount everest and decided not to any more due to the 1,000s of people making a line on the mountion

explanation: