Assuming you are using a WD setup, that may be the culprit and depending on the brand, it is just something they do and you need to be a little careful in "lubricating" the noise out...quite often that noise is caused by the "anti-sway" feature of those bars and lubrication can quieten them down at the sacrifice of the "anti-sway" capability. Consult the manufacturer before lubricating an anti-sway WD system.
You don't mention which model TT you have, but, another source of "popping" noises in turns, on tandem axle trailers, is the suspension flexing during the turn. You have two wheels/axles very close together and they "deform" drastically in tight turns and that "popping" noise is the suspensions movement in the connections to the frame. Normal and not a lot you can do about it.
My 2 cents, your mileage may vary...
2 Cats; J-Lo and Ragamuffin :R
2014 Thor Tuscany 40RX DP
2011 Ram 2500 Longhorn CTD HO
2011 Keystone Cougar 318SAB (now gone)
2008 FunFinder X 210WBS (Sadly gone)