Yes, the Constitutional Convention was a runaway convention, an attempt to resolve issues with the existing Articles of Confederation.
However ...
Neither the runaway Constitutional Convention, nor any such Convention in the future, produced a ratified new Constitution, but a proposed new Constitution for the states to later ratify if they so choose. This is because, after the delegates to the Convention had finished and signed the final draft, they then had to get out and sell the draft to the states for ratification, just as the states would have to ratify any amendments proposed by future Conventions.
"The Constitution was adopted on September 17, 1787, by the Constitutional Convention in Philadelphia, Pennsylvania, and ratified by conventions in eleven States." --United States Constitution, Wikipedia.
Precisely!