I came across this problem, wanting to figure it out too.
I tried keeping it in the hot water about 1/3 of the way up the can, can already open, spoon in hand, and get this, coffee cream, like the nice ones. This one was already a caramel creamer so it matched perfectly, but a flavor addition might render a more complex and unique dulce. I added it in slowly while it was still hot, doing about a 1 Tbs at a time. Went from being chunky and thick to creamy and drizzly. So there you go. Little trick that will save your dulce and depending on the liquid creamer you have, add a unique twist to the dulce de leche. If you're wondering, I used Simply Pure coffee creamer, Caramel flavor. Maybe try Bailey's or whatever your favorite is. I salvaged my can for my cake!