Are you using the NoTubes yellow rim tape or NoTubes 'rim strips'? Rim strips do give a better seal to the tyre and help prevent burping IME.
What rims are you using? I'm guessing they're non UST.
I have had similar problems - expensive UST tyres easily pinch flatting on fast rocky terrain or burping air on fast hard pack turns.
On rocky terrain I now run a Maxxis Dual Ply rear, non-UST tyre but running it tubeless with lots of latex. If you use plenty of washing up liquid, it's realtively easy top get them to seal on either a UST rim (I'm running Easton Haven's) or on other rims with a rim strip (harder to get it, ahem, up with just yellow tape but not impossible.)
This works really well and as long as the tyre pressure is up around 30-35psi, I get no burping and no pinch flats. I just spent a whole week riding in Verbier on the fastest, rockiest trails I've ever done and didn't have a single issue with this set up.
The alternative to this would be to run a dual ply tyre with an inner tube but given how heavy the tyres are, I am glad to save the extra weight.
If you are running a dual ply tyre (and I think you are since you state your tyres are 2.5" and I don't think Maxxis make a 2.5" tyre that isn't dual ply) then you may be able to get away with regular/light weight inner tubes, certainly on the front, maybe not on the back, but like I say, you can run non-UST tyres tubeless quite easily.