If you just want to serialize for debugging purposes, the shorter way is to use String.Join:

var asString = string.Join(Environment.NewLine, dictionary);

This works because IDictionary<TKey, TValue> implements IEnumerable<KeyValuePair<TKey, TValue>>.

Example

Console.WriteLine(string.Join(Environment.NewLine, new Dictionary<string, string> {
    {"key1", "value1"},
    {"key2", "value2"},
    {"key3", "value3"},
}));
/*
[key1, value1]
[key2, value2]
[key3, value3]
*/