Why sometimes my connection speed goes beyond the limit?

Hi,

it happens rarely that my connection speed far exceeds my broadband speed provided by the ISP. Mine is 2Mb/s that is around ( 256 KB/S in theory by converting) but in reality i don't pass 232 KB/S. Three days ago i tried to download a software of a 10 mb size and the speed was around 850 KB/S !! it kept around this speed during all the download. I thought it was a coincidence or something went wrong, i repeated the same download and same thing happened ! i then tried downloading other stuff but my speed was back to normal, it worked only with that download !! i can't understand why this happens ? anyone has an explanation... this is not the first time it happened , once i tried to download naruto and and for the whole 175 mb size, the speed was over 1MB ! this is beyond my limit, i'd love to hear an answer , thank you.

what do you mean?? managed to do what? exceed the speed limit provided by ISP? using VPN ?? i can't even imagine that.