08 Milan Brake issue- Help

Was driving last night approaching red light and felt a sudden (pop) in the brake system. Went from strong brakes to suddenly very mushy. Was lucky it was late and no traffic out and was able to stop OK. I suspect the master cyl. since it happened suddenly. Was a little low on brake fluid but nothing to explain this type of failure. Brakes have had no recent service and were working fine--- I am going to take a close look today and open for suggestions!

More likely a wheel cylinder or a caliper.

More likely a wheel cylinder or a caliper.
Bled all the brakes and everything was great---for over a year and now same sh*t. Last time I noticed was very low on brake fluid before I started bleeding---But not this time---fricken fluid level good and driving around with mushy brakes--gotta diagnose-- hazardous! Any thoughts---I'm open--Parked the thing till I get a day off. Always hear or feel a ""POP"" >>??

Check out from the expert, it some time happen when car run at highest speed. I just like to know that because it was happed with me...
At that time cylinder is the main root of this problem...