Wrong dereference => Out of memory

schetchik has asked for the wisdom of the Perl Monks concerning the following question:

Hello!

Could you explain, why does wrong dereference make my Perl out of memory

$ perl -e 'my $a = [{ test => { val => 1 } }, { test => { val => 2} }]
+;print $a->{test}->{val}, "\n"'
Out of memory!
[download]

I use perl 5.8.8

Thank you