Wow!  Now that's a great answer!

Let me just add the following, since it took me a few minutes to see exactly what you were doing, as well as making it conform to the original requirements for the output:

$_ = "abc";    # Regex match of /.../ uses $_ when =~ is unspecified 

# Nicely solves the problem stated, and demonstrates list assignment
# to a regex capture.
#
@matches = m/(((a)b)c)/ and print join "\n", reverse @matches;
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I realized a "reverse" was necessary, and then immediately fell into the trap of putting it before the "join".  I like your answer a lot for its succinct approach!