break

You can use break to break out of a while loop:

a = 2
while (a += 1) < 20
  if a == 10
    break # goes to 'puts a'
  end
end
puts a # => 10

break can also take a parameter which will then be the value that gets returned:

def foo
  loop do
    break "bar"
  end
end

puts foo # => "bar"