Pygame random bouncing

I'm making a Breakout in Pygame, but, to add some challenge, I want the ball to be bouncing in a random but still logic way. For example : If the ball goes both up (y) and right (x), if it bounces on a brick, it will not simply revert its y direction nor go back the left side of the screen it came from (which wouldn't make sewnse), but it will have a new, random direction and speed, so it is not too predictable or repetitive and gets boring (I hope I made this clear enough :p).

class Ball(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.Surface([10, 10])
        self.image.fill(white)
        self.rect = self.image.get_rect()
        self.speed_x = 1
        self.speed_y = 1
        self.direction = [random.randint(0, 1), random.randint(0, 1)]
        self.lives = 5

    def update(self):
        self.rect.x += self.speed_x
        self.rect.y += self.speed_y

        # Wall and Paddle Bounces
        if self.rect.y > 500:
            self.lives -= 1
            pong.rect.x = 375
            pong.rect.y = 320

        if self.rect.y < 1:
            self.speed_y = 1

        if self.rect.x > 740:
            self.speed_x = -1

        if self.rect.x < 1:
            self.speed_x = 1

        if self.rect.colliderect(paddle1.rect):
            self.speed_y *= -1

        for brick in brick_list :
            if pong.rect.colliderect(brick.rect) :
                self.speed_y *= -1
                brick_list.remove(brick)

I tried various methods (like simply randoming self.speed_x and self.speed_y, but everytime, the ball gets stuck or has a really weird behavior. Any explanation / solution ?