As I know you are capable of figuring it out, go here
and download Wireshark and install that. Also allow it to install WinPCap should it ask. Then run Wireshark.
, then use the drop down at the top to select your current connection. Also make sure this is checked:Automatic scrolling in live capture
Then click Start
. If you see no activity in the log you have selected the wrong Interface (net connection device). The activity of interest will be hilighted green.
Watch for large groupings of similar net activity that might suggest these spurts you are mentioning. You'll have to tweak with Wireshark a little to get the hang of it.
If you see a "TCP segment", right click that and select "Follow TCP stream". This will tie together/reassemble the segmented packets into the entire packet, which may provide info as to what is being sent, and for what reasons.