Black trail (beam) in the sky suddenly appears and disappears

My girlfriend and I were driving back home on highway 50 going east in Gatineau at about 13:00 and as we got to Montée Paiement exit, we noticed a black trail in the clear blue sky. It suddenly appeared, lasted about 6 seconds and dissappeared after that.  It looked similar to white trails made by commercial air planes, but was black in colour and very sharp, not blurred like the white trails (looked like a beam or laser almost).  The odd thing is how it just suddenly appeared and dissappeared again within 6 seconds. It started from the east end of the sky and ended towards the west. The line didn't start to appear and become longer, it appeared entirely all at once.
 About 5 seconds after it vanished, we saw a commercial plane that just came out of nowhere, starting to make a white trail, but the plane started by doing a very very sharp turn next to where the black trail started and then it flew back in regular linear trail...
 It was just weird to see this plane pop-up out of nowhere, doing a very sharp turn (for a commercial air plane) and starting to leave a white trail instead of having a linear trail already following behind it.  The plane seemed very high in the sky(35,000ft+), not like in just took off from an airport .
 Anybody else seen these black trails in the sky? My girlfriend thinks it's normal and was probably made by a plane, but I told her how does a trail just suddenly appear out of nowhere and disappear again and on top of that, why haven't we seen blacktrails in the past (5, 10 or 15 years ago) ? This is new to me.