my %queries_by_key = (); # Hash of arrays

my $number_of_queries = scalar @all_queries;

for (my $i = 0 ; $i < $number_of_queries; ++$i) {
    my %query = %{ pop @all_queries }; # value of pop() is a hash

    foreach my $query_key (keys %query) {
        # Treat each value in %queries_by_key as an anonymous array
        push @{ $queries_by_key{$query_key} }, $query{$query_key};
    }
}

foreach my $key (sort keys %queries_by_key) {
     print "$key has ";
     print join ',', @{ $queries_by_key{$key} }; # treat as an array 
     print "\n";
}