To reach a point from which one cannot proceed further, either because of a physical obstacle or because of some forbidding circumstance.
Our car came to a dead end; the only way to get out was to drive back in reverse.
The factory expansion project came to a dead end because of a lack of funds.
To end, to stop.
This idiom is used with finally and never when some activity lasts too long.
Even though my friend seemed to enjoy the movie, I thought that it would never come to an end.
The meeting finally came to an end at ten o’clock in the evening.